Page 54 - Slipped Capital Femoral Epiphysis Pathogenetic and Clinical aspects

Chapter 3
The same results were seen in only the NT SCFE group, where the relative risk over the 13 years was 0.99 (95 % CI 0.82–1.18) (Table 4). The annual incidence of NT SCFE for girls also increased significantly (p < 0.001), but not for boys or the combined group (p = 0.309 and p = 0.293, respectively) (Fig. 2).
Age
In the combined NT and T SCFE group, 499 of the 609 patients (82 %) with SCFE were between 10 and 14 years of age (Fig. 3). The T SCFE group contained more boys in the age group 10–14 years, whereas the NT SCFE group contained more girls (Fig. 4). In the age group 10–14 years, the incidence rates for boys and girls did not differ significantly (relative risk 0.92, 95 % CI 0.77–1.10). In the age group 15–19 years, the incidence rates did differ: 4.3:100,000 for boys and 0.6:100,000 for girls. One possible explanation for this effect could be the earlier closure of the growth plate in girls (around 14 years of age) than in boys (around 16 years of age). In the age group 5–9 years, we observed the opposite effect: the incidence for boys was 0.6:100,000 and that for girls was 1.2:100,000.
Discussion
Our data show that the presumed gender dominance in the incidence of SCFE was not confirmed in the interval 1998–2010 in the Netherlands. The data also show an increase in the incidence of surgical procedures for SCFE in girls starting from 1998.
The strong points of this study are its nationwide coverage and the use of uniform diagnostic criteria.
One limitation to our study is our use of national Dutch hospital registration data, which did not allow us to take into account the etiology of SCFE (i.e. endocrinological, mechanical or other causes). NT SCFE is sometimes confused with T SCFE and often treated as such. Therefore, we combined the T/NT SCFE groups and also considered the NT SCFE group separately. The T SCFE group may have contained some high-energy epiphyseal fractures, leading to an overestimation of T SCFE. However, we expect this over-estimation to be very small because of the low frequency of this type of fracture in general and the low number of high-energy lesions in the Netherlands. A second limitation to our study is that the statistics did not show whether patients had a unilateral slip or a bilateral slip nor could we find information on different cultures or seasonal variations.
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